If you were an alien sensing radio waves a city for you would be the same as a bright day for us: we are used to lots of visible light being scattered around, and the aliens would be used to radio doing the same.

We see in the visible part, yet we are not blinded by all the light.

Because you tried two different OSes and the point where it hangs is the point where the OS sends an APM/ACPI command to reboot / power off. This is the last thing the OS does. So if that’s not happening something is wrong with the hardware, BIOS, or BIOS settings.

You could try the syslog (journalctl), but logging is probably already off at that point.

Yeah that seems like a mainboard issue.